Proctodeum

Proctodeum is the posterior part of the alimentary canal, which includes the rectum and anus. It is derived from the embryonic hindgut and is an important part of the digestive system.

Development

The proctodeum forms during the fourth week of embryonic development. It begins as a depression in the ectoderm at the base of the tail region. This depression, known as the anal pit, deepens to become the proctodeum. The proctodeum and the hindgut are initially separated by the cloacal membrane, which eventually breaks down to form the anus.

Structure

The proctodeum includes the distal third of the rectum and the anus. The rectum is the final section of the large intestine that terminates at the anus. The anus is the external opening where the digestive tract ends and exits the body. The proctodeum is lined by stratified squamous epithelium, which is different from the simple columnar epithelium that lines the rest of the digestive tract.

Function

The main function of the proctodeum is to store and expel feces from the body. The rectum stores the feces until it can be eliminated. The anus is the final part of the digestive tract and controls the expulsion of feces, the waste product of digestion.

Clinical significance

Abnormalities in the development of the proctodeum can lead to a number of congenital disorders, including imperforate anus, anal atresia, and cloacal exstrophy. These conditions require surgical correction soon after birth.

See also

• Digestive system
• Embryonic development
• Rectum
• Anus